1. Field
This disclosure relates generally to particulate filters and, more particularly, to particulate filters for the nose and mouth of a user.
2. Background
The World Health Organization has estimated that about 7 million people died from air pollution in 2012 and that, in general one-eighth of all global deaths are linked to air pollution. Of greatest health concern is pollution made up of fine particulate matter of 2.5 microns in diameter or less (called “PM2.5”), which is typically, but not exclusively, made up of mineral dust, sulfate and soot particles from burning coal, wildfires and volcanic eruptions, and black carbon from agricultural burning and engine exhausts. Colloquially referred to as “haze”, the problem of airborne particulate matter is greatest across a broad swath of the Earth, stretching from the Saharan Desert in Northern Africa through the Middle East, Northern India and into Eastern Asia, in Borneo, Thailand, and with heaviest concentrations being observed in parts of China. When compared with maps of population density, it has been estimated that more than 80% of the world's population breathe polluted air that exceeds the World Health Organization's recommended level of 10 micrograms of particulate matter per cubic meter.
While levels of particulate matter are comparatively low in the United States, pockets have been identified, through satellite analysis, over urban areas in the Midwest and East. Likewise, high levels of particulate matter have been identified through satellite analysis in at least part of the Mexican state of Chihuahua, and to a lesser extent, elevated levels have been detected in pockets of Western Europe as well.
The biggest problem with PM2.5 is that PM2.5 particulates are small enough to bypass the natural filtration provided by nasal hairs and nasal mucus and thereby can enter the lungs, and in some cases, even pass into the bloodstream. As such, PM2.5 can damage lung tissues, cause inflammation that can cause or aggravate respiratory and cardiovascular disease, can cause placental blood toxicity in pregnant women exposed during the first month of pregnancy, and may lead to certain forms of cancer. Adverse health effects have been associated with exposures to PM2.5 over periods as short as a day, with greater affects being seen from longer exposure. People who are most at risk are people suffering from asthma or battling influenza, those with lung, heart, or cardiovascular disease, and particularly the elderly, and children and it is routine for haze warnings to be issued when the outdoor Air Quality Index (“AQI”) exceeds 100. An AQI of 100 roughly corresponds to a PM2.5 level of 40 micrograms per cubic meter of air (averaged over 24 hours), which is slightly more than the short term standard for potentially harmful PM2.5 exposure established by the Environmental Protection Agency (“EPA”) of 35 micrograms per cubic meter of air.
In an attempt to avoid exposure, particularly in Asian countries, people have resorted to wearing low cost surgical face masks widely available from, among other places, convenience stores. However, such masks are generally not effective because they are designed to prevent the spreading of germs and disease through the exhalation and expulsion of germs by the user and the inhalation of most pollens (which are typically larger than PM2.5). Moreover, such masks are uncomfortable, because they require straps that loop around the user's ears to hold them in place and they substantially block the entire lower portion of the user's face. As a result, they are an impediment to, for example, the user eating and/or drinking, blowing their nose, etc., requiring them to remove the mask to perform those activities.
Enhancements to such masks to provide for better filtration of PM2.5 have been attempted, for example, through the addition of a layer of activated carbon or more specialized filters, but such enhancements can significantly increase the cost, size and obtrusiveness of the masks, making them unsuitable for mass use, particularly in poorer areas of the world where the problem is greatest.
In an effort to avoid some of those issues, attempts have been made to create filtering devices that are inserted as plugs into a user's nostrils to augment or supplant the natural particle catching ability of the nose itself. Thus, while such devices allow for eating and drinking, those filtering devices they do not allow for blowing one's nose without removal and do nothing to prevent particulate matter from entering the body via the mouth. In addition, those devices, being foreign bodies to the nasal cavities and bulky, can themselves trigger sneezing responses in the putative user, rendering them unusable. Even as to users who do not have a sneezing response to such devices, since they must block the nasal passages, they are often uncomfortable to wear and, some types, can be dislodged by strong exhalation or naturally simply through normal breathing over time, leading many users to dispense with using them entirely.
Thus, there is a significant need for a filtration device that can reduce potentially harmful PM2.5 exposure and that does not require insertion into the nostrils, is not as obtrusive as a face mask, and conveniently allows for eating and drinking when necessary.